Adhesion promoters for one-component RTV silicone compositions

ABSTRACT

A self-bonding alkoxy-functional one-component RTV composition which contains as a self-bonding additive a silane which is functionalized by radicals selected from amino, ether, epoxy, isocyanato, cyano, acryloxy, and acyloxy. Such a composition is also shelf-stable and substantially non-corrosive.

BACKGROUND OF THE INVENTION

The present invention relates to one-component RTV silicone rubbercompositions, and more particularly the present invention relates toadhesion promoters or self-bonding additives for one-component RTVcompositions.

An early type of one-component RTV composition is to be found in thedisclosure of Ceyzeriat, U.S. Pat. No. 3,133,891 and Bruner, U.S. Pat.No. 3,035,016. These disclosures relate to acyloxy functionalone-component compositions. In the course of time there were variousinventions made of other types of RTV compositions having differentfunctionalities; for instance, one-component ketoxime functional RTVcompositions; amine functional RTV compositions; amide functional RTVcompositions; aminoxy functional RTV compositions, etc.

During the course of development of such compositions, it was decidedthat it would be desirable for such compositions to have self-bondingadditives; that is that the composition bond without a primer to varioustypes of substrates with good adherency by the incorporation of suchself-bonding additives. Examples of such self-bonding additives for suchacyloxy functional RTV compositions are, for instance, to be found indisclosures of Kulpa, U.S. Pat. No. 3,296,161, Goossens, U.S. Pat. No.3,296,195 and Beers, U.S. Pat. No. 3,438,930. The difficulty with suchacyloxy functional compositions was that they were somewhat corrosive.That is, even though they were fast-curing and had other advantageousproperties, they were found to be somewhat corrosive and gave off apungent odor. Accordingly, it became desirable to develop compositionsthat were substantially non-corrosive and did not give off objectionableodors such that could be used in a crowded room. As stated previously,such compositions were one-component.

An example of a two-component RTV composition is, for instance,disclosed in Nitzsche et al U.S. Pat. No. 3,127,363. This patentdiscloses two-component compositions comprising a silanol polymer, apolysilicate cross-linking agent and preferably a tin salt of acarboxylic acid as a catalyst. While such a composition is packaged as atwo-component system when it is desired to cure the composition the twocomponents are mixed and the composition cures to a silicone elastomer.While such a composition had a sufficiently rapid curing time and wasnon-corrosive, nevertheless it had to be mixed prior to the use of thecomposition which necessitated additional labor costs. Further, thecomposition once it was mixed did not have an extended shelf life. Anearly one-component system is to be found in Nitzsche et al. U.S. Pat.No. 3,065,194 which discloses the utilization of a silanol polymer, analkoxysilane cross-linking agent and a tin soap. While such acomposition was one-component, nevertheless the composition did not havea sufficient shelf life. Further, special mixing procedures had to beutilized to prepare the composition, that is an extended drying cycle.

It was early recognized that such alkoxy functional one-component RTVsystems had many advantages, and attempts were made to prepare suchcompositions as disclosed in Brown et al, U.S. Pat. No. 3,122,522 andBrown et al, U.S. Pat. No. 3,161,614, or U.S. Pat. No. RE-29760.However, these compositions did not have a sufficiently fast cure rateand had very poor shelf stability. Other alkoxy functional RTVcompositions, for instance are to be found in Weyenberg U.S. Pat. No.3,334,067, Cooper et al, U.S. Pat. No. 3,542,901, Smith et al, U.S. Pat.Nos. 3,689,454 and 3,779,986. These latter patents and specifically theWeyenberg and the Smith patent utilize specialized titanium chelatecatalysts as condensation catalysts for such alkoxy functionalone-component RTV compositions. Such titanium chelate catalysts weredesirable in that they imparted to the alkoxy functional RTV acommercial cure rate; that is, the cure rate was such that thecomposition could be commercialized. However, the composition was stillnot a fast-curing one-component RTV system.

Another attempt to make such composition fast-curing and also havedesirable shelf stability properties and self-bonding properties is tobe found in the disclosure of Beers, U.S. Pat. No. 4,100,129. However,such composition still was not as fast-curing and still did not have asgood a shelf stability as would be desirable.

It has been theorized recently that such earlier compositions sufferedfrom the fact that there was excess methanol, silanol or hydroxy groupsin the polymer system after it had been prepared even though it wasprepared in the substantial absence of moisture. Such hydroxy groups inthe polymer system resulted in the premature cross-linking of thepolymers such that there resulted a poorly curing composition, that isone that did not have a sufficient cure rate and a good shelf stability.Accordingly, a system was devised in which there could be utilized ascavenger in the composition to react with excess hydroxy groups whetherfrom methanol, silanol, or water, and would not react with the alkoxygroups to prematurely cross-link the RTV system. The disclosure of howthis is accomplished as well as the scavenging systems for such acomposition is for instance disclosed in the patent of White et al, U.S.Pat. No. 4,395,526 and in the patent of John B. Halgren, U.S. Pat. No.4,377,706. The compositions of White, et al while sufficientlyfast-curing and having shelf stability, nevertheless, had to be modifiedto meet certain requirements; that is, such compositions did not bond tomost substrates. In the absence of a primer such compositions have verylittle or no self-bonding properties. Accordingly, it became highlydesirable to develop self-bonding additives for such compositions. Itshould be noted that in addition to the self-bonding additives disclosedbefore, there are other patents on useful self-bonding additives forboth two-component and one-component RTV systems. (RTV in thisapplication refers to room temperature vulcanizable.) For instance, noteBessemer et al, U.S. Pat. No. 3,888,815 which relates to self-bondingadditives for two-component RTV systems in which the functionality ofthe self-bonding additives, which in addition to alkoxy, may be selectedfrom amino, carbonyl, carboxy, isocyano, azo, diazo, thio, thia, dithia,isothiocyano, oxo, oxa, halo, ester, nitrose, sulfhydryl,hydrocarbonylamido, sulfonamido and combinations thereof. Also note thedisclosure of Smith, U.S. Pat. No. 4,147,685 which relates to primercompositions and specifically the acrylate functional silanes of thatpatent which may be utilized as self-bonding additives for RTVcompositions and disclosed in the patent application of Keating, Ser.No. 109,727, filed on Jan. 4, 1980.

Other disclosures on self-bonding additives for RTV systems for instanceare to be found in Beers, U.S. Pat. No. 4,100,129 which was referred topreviously and Mitchell et al, U.S. Pat. No. 4,273,698. The Mitchell etal patent discloses various silyl fumarates, succinates, and maleateswhich can be utilized as self-bonding additives in one-component RTVsystems. However, none of these patents which are all incorporated byreference in the present case, disclose self-bonding additives for thecompositions of White et al, U.S. Pat. No. 4,395,526. A self-bondingadditive is desirable, otherwise there has to be utilized a primer. Theuse of a primer involves added labor costs which are considerably morethan the additional cost of a self-bonding additive when it isincorporated into the composition during the manufacture of thecomposition. Accordingly, it is highly desirable to have a self-bondingadditive or additives in the compositions of White et al, U.S. Pat. No.4,395,526.

It is one object of the present invention to provide for adhesionpromoters or self-bonding additives for one-component alkoxy functionalRTV compositions.

It is an additional object of the present invention to provideself-bonding additives for alkoxy functional, one-component RTV systemswhich self-bonding additives will give self-bonding properties to theRTV compositions and to most substrates.

It is yet an additional object of the present invention to provideadhesion promoters or self-bonding additives to alkoxy-functionalone-component RTV systems which have a fast cure rate and are shelfstable and which self-bonding additives will affect the physicalproperties and the curing properties of the RTV system.

It is a further object of the present invention to provide a process forproducing a self-bonding one-component alkoxy-functional RTV systemwhich has a fast cure rate, and is shelf stable by incorporating in theRTV system self-bonding additives.

These and other objects of the present invention are accomplished bymeans of the disclosures set forth herein below.

SUMMARY OF THE INVENTION

In accordance with the above objects, there is provided by the presentinvention a stable, substantially anhydrous, and substantially acid-freeroom temperature vulcanizable organopolysilazane composition, having aneffective amount of an adhesion promoter having the formula, ##STR1##where R¹⁰, R¹¹ are C₁₋₈ monovalent hydrocarbon radicals, t varies from 0to 3 and Z is a saturated, unsaturated or aromatic hydrocarbon residuewhich may be further functionalized by a member selected from the classconsisting of amino, ether, epoxy, isocyanato, cyano, acryloxy andacyloxy and combinations thereof.

The most preferred self-bonding additives within the scope of Formula 1are the amine functional silanes, then the epoxy functional compounds,and finally the other compounds coming within the scope of Formula 1.There is also envisioned by the present invention a process for formingsuch RTV compositions within the scope of the instant invention.

The self-bonding additives are most preferably applied to an end-cappedpolymer, that is a one-component RTV composition in which first thecross-linking agent is added to a silanol polymer preferably in thepresence of a catalyst as disclosed in White et al, U.S. Pat. No.4,395,526, and that after the end-capped polymer is formed, thescavenger is added so as to absorb the excess hydroxy groups in thepolymer system. After the scavenger has absorbed the excess hydroxygroups in the system, then the tin soap condensation catalyst is addedand the other ingredients so as to form the final composition. In thisway, the most advantageous composition, that is, a fast-curing,non-corrosive, self-bonding, RTV composition is obtained which has goodshelf stability.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present case relates to adhesion promoters or self-bonding additivesfor a particular type of one-component RTV silicone rubber composition.It is necessary now to give some description of such one-component RTVcomposition. For a fuller description of such a composition, one isreferred to the disclosure of White et al, U.S. Pat. No. 4,395,526,which has been referred to previously.

There are certain expressions that are used in this application; one isreference to the composition as a "stable" composition.

As utilized hereinafter, the term "stable" as applied to theone-package, polyalkoxy-terminated organopolysiloxane RTV's of thepresent invention means a moisture curable mixture capable of remainingsubstantially unchanged while excluded from atmospheric moisture andwhich cures to a tack-free elastomer after an extended shelf period. Inaddition, a stable RTV also means that the tack-free time exhibited byfreshly mixed RTV ingredients under atmospheric conditions will besubstantially the same as that exhibited by the same mixture ofingredients exposed to atmospheric moisture after having been held in amoisture resistant and moisture-free container for an extended shelfperiod at ambient conditions, or an equivalent period based onaccelerated aging at an elevated temperature.

Another expression that is used is "substantially acid-free," withrespect to defining the RTV silicone composition. The expression"substantially acid-free" with respect to defining the elastomer madefrom the RTV composition of the present invention upon exposure toatmospheric moisture means yielding by-products having a pKa of 5.5 orgreater with 6 or greater preferred, and 10 or greater beingparticularly preferred.

Proceeding now to the RTV composition, the present invention is based onadhesion promoters for stable, substantially acid-free, one-packagemoisture curable polyalkoxy terminated organopolysiloxane RTVcompositions, which are made by using a silanol terminatedpolydiorganosiloxane consisting essentially of chemically combineddiorganosiloxane units of the formula ##STR2## such as asilanol-terminated polydiorganosiloxane of Formula (8) below, where R isas defined below with an effective amount of certain silane scavengersfor chemically combined hydroxy radicals. In the silanol-terminatedpolydiorganosiloxane consisting essentially of chemically combinedFormula (2) units, the presence of silicon bonded C.sub.(1-8) alkoxyradicals such as methoxy radical is not precluded. The hydroxy radicalswhich can be removed by the silane scavenger can be found in materialsnormally present in the RTV composition of the present invention, forexample, trace amounts of water, methanol, silanol radicals on thesilica filler (if used), the silanol polymer of Formula (8), or asilanol-terminated polymer having Formula (2) units. The silanescavenger useful for eliminating chemically combined hydroxy radicals inaccordance with the practice of the invention preferably has theformula, ##STR3## where R¹ is a C.sub.(1-8) aliphatic organic radicalselected from alkyl radicals, alkylether radicals, alkylester radicals,alkylketone radicals and alkylcyano or a C.sub.(7-13) aralkyl radical,R² is a C.sub.(1-13) monovalent organic radical selected from R radicalsas previously defined, and defined more particularly below, X is ahydrolyzable leaving group selected from amido, amino, carbamato, enoxy,imidato, isocyanato, oximato, thioisocyanato, and ureido radicals.Desirable members are amino, amido, enoxy, and the more preferred isamino, for example, N-C.sub.(1-8) alkyl C.sub.(1-8) acylamino, a is aninteger equal to 1 or 2 and preferably 1, b is a whole number equal to 0to 1 and the sum of a +b is equal to 1 or 2. In Formula (3), where a is2, X can be the same or different. The leaving group X reactspreferentially before --OR¹ with available --OH in the RTV compositionand provides an RTV composition substantially free of halogen acid, orcarboxylic acid. The silane scavenger of Formula (3) is both the silanescavenger for hydroxy functional groups and a polyalkoxysilanecross-linking agent for terminating the silicone atom at eachorganopolysiloxane chain-end with at least two alkoxy radicals.

Among the ingredients of the RTV compositions which are formed as aresult of the use of the hydroxy scavenger of Formula (3), issilanol-free polydiorganosiloxane, chain-terminated with two or three--OR¹ radicals. The silanol-free polydiorganosiloxane optionally can becombined with an effective amount of a cross-linking silane, as definedhereinafter, under substantially anhydrous conditions. The cross-linkingpolyalkoxysilane which can be utilized in combination with thescavenging silane of Formula (3) has the formula, ##STR4## where R¹, R²and b are as defined above. The preferred condensation catalysts whichcan be used in the practice of the invention include metal compoundsselected from tin compounds, zirconium compounds, and titanium compoundsor mixtures thereof. Additional condensation catalysts which can be usedare defined more particularly hereinafter.

It is not completely understood why the polyalkoxy-terminatedorganopolysiloxane compositions of the present invention are stable inthe presence of certain condensation catalysts over an extended periodof time in the substantial absence of moisture.

It is postulated that excess hydroxy groups whether in the form of analcohol or silanol groups or water will cross-link and prematurely curethe polyalkoxy polymer in the package or alcohol groups may end-capsilanol polymers with monoalkoxy groups. If this occurs, then this isone the reasons it is believed that the cure rate of the polymer willslow down with the passage of time.

The use of the silane scavenger for hydroxy of Formulas (3) or (5)below, in which the leaving group X is not a halogen radical,substantially eliminates undesirable water in the filler and siliconepolymer, as well as residual moisture in the RTV composition during theshelf period. In determining what level of silane scavenger of Formula(3) or (5) to use in the practice of the invention, the total hydroxyfunctionality of the RTV composition can be estimated. The total hydroxyfunctionality of the polymer can be determined by infrared analysis. Inorder to insure that an effective or stabilizing amount of scavenger isused to maintain the stability of the composition over an extended shelfperiod of six months or more at ambient temperature while in a sealedcontainer, there can be used an additional amount of scavenger over thatamount required to endstop the polymer. This excess of scavenger can beup to about 3% by weight, based on the weight of the polymer. Theaforementioned 3% of scavenger by weight exceeds that amount required tosubstantially eliminate available hydroxy functionality in the polymeras a result of reaction between OH functionality and X radicals. Incompositions which also contain filler and other additives, theadditional amount of scavenger of Formulas (3) or (5) below which isrequired is estimated by running a 48-hour stability check at 100° C. todetermine whether the tack-free time remains substantially unchanged ascompared to the tack-free time of the composition before aging measuredunder substantially the same conditions.

Where polyalkoxy-terminated polymer of Formula (6) below is made withoutusing silane scavenger of Formula (3), a silane scavenger can be used inthe practice of the invention having less than two --OR¹ radicalsattached to silicon, as shown by the formula, ##STR5## where R¹, R², andX are as previously defined, c is a whole number equal to 0 to 3inclusive, d is an integer equal to 1 to 4 inclusive, and the sum of(c+d) is equal to 3 or 4. In such situations, the scavenging silanes offormula (5) can be used in an amount sufficient to stabilize the RTVcomposition as previously defined for the scavenging silane of Formula(3). In addition, there can be used with scavengers of Formulas (3) or(5) at least 0.01 part and up to 10 parts of the cross-linking silane offormula (4).

The polyalkoxy-terminated organopolysiloxane of the present inventionhas the formula, ##STR6## where R, R¹, R², X, n and b are as previouslydefined and e is equal to 0 to 1 and the sum of b+e is equal to 0 to 1.The polyalkoxy-terminated organopolysiloxane of Formula (6), can be madeby various procedures. One procedure is taught by Cooper et al U.S. Pat.No. 3,542,901 involving the use of a polyalkoxysilane with asilanol-terminated polydiorganosiloxane in the presence of an aminecatalyst. A method not taught by Cooper et al is the use of the silanescavenger of Formula (3) as an end-capper with silanol-terminatedpolydiorganosiloxane used in the practice of the invention.

In Formulas (1-6), R is preferably selected from C.sub.(1-13) monovalenthydrocarbon radicals, halogenated hydrocarbon radicals and cyano alkylradicals, R¹ is preferably a C.sub.(1-8) alkyl radical or a C.sub.(7-13)aralkyl radical R² is preferably methyl, phenyl, or vinyl.

The preferred X radicals in Formulas (3), (5) and (6) are amido, aminoand enoxy, and the most preferred is amido.

It has been found advantageous to end-cap the silanol polymer with thecross-linking agent of Formula (4) first and then to add a scavenger soas to absorb all free silanol in the mixture. Accordingly, it isdesirable to produce a polyalkoxy end-cap polymer as disclosed above inthe production of the RTV composition and then add a scavenger in thecomposition so as to absorb all the moisture such that when the fillerand other ingredients are added that any moisture in those ingredientswill be absorbed by the scavengers and will not operate to degrade thesystem. Of course, it must be understood that the cross-linking agentand the silanol polymer must be as dry as possible with the exception ofthe silanol groups in the polymer. The preferred process for doing thisis to take the silanol polymer, react it with a cross-linking agent suchas methyltrimethoxysilane in the presence of a condensation catalystwhich may be one of the condensation catalysts disclosed in the White etal patent, U.S. Pat. No. 4,395,526, such as for instancedi-n-hexylamine. Other amines may be utilized as condensation catalystsas disclosed in the foregoing U.S. Pat. No. 4,395,526. Once thepreferred end-capped polymer is produced, then the scavenger is addedalong with the other ingredients so that the scavenger absorbs theexcess hydroxy groups that may be present in the end-cap polymer as wellas absorb the moisture in the filler and other ingredients that areadded to produce the one-component RTV system.

It has been further found that improved cure rates can be achieved ifminor amounts of amines, substituted guanidines, or mixtures thereof,are utilized as curing accelerators in the polyalkoxy compositions ofthe present invention. These curing accelerators also serve to catalyzethe ability of the enoxy leaving group to act as a scavenger. There canbe used from 0.1 to 5 parts, and preferably from about 0.3 to 1 part ofcuring accelerator, per 100 parts of the silanol-terminated polymer ofFormula (1), or which consists of chemically combined units of Formula(2), or 100 parts of the polyalkoxy-terminated polymer of Formula (6) tosubstantially reduce the tack-free time (TFT) of the RTV composition ofthe present invention. This enhanced cure rate is maintained after ithas been aged for an extended shelf period, for example, 6 months ormore at ambient temperatures, or a comparable period under acceleratedaging condition. Its cure properties after the extended shelf periodwill be substantially similar to its initial cure properties, forexample, tack-free time (TFT), shown by the RTV composition upon beingfreshly mixed and immediately exposed to atmospheric moisture.

It appears that the curing accelerators described herein, in addition todecreasing the tack-free times of the RTV compositions of thisinvention, also provide a surprising stabilizing effect for particularRTV compositions catalyzed with certain condensation catalysts whichexhibit a marked lengthening of tack-free time after accelerated aging.For this class of condensation catalysts, addition of amines,substituted guanidines and mixtures thereof described herein providestable RTV compositions which exhibit a fast cure rate initially, i.e.less than about 30 minutes which remains substantially unchanged afteraccelerated aging.

The RTV compositions of the present invention can cure to a depth of1/8" thickness within 24 hours. Durometer Hardness (Shore A) can then bedetermined and used to evaluate the cure of the compositions as shown inthe examples.

In broader aspect, the present invention comprises a one-componentsubstantially anhydrous room temperature vulcanizable organopolysiloxanecomposition stable under ambient conditions in the substantial absenceof moisture over an extended period of time and convertible to asubstantially acid-free tack-free elastomer comprising: (1)organopolysiloxane with a silicon atom in each polymer chain endterminated with at least two alkoxy radicals; (2) an effective amount ofcondensation catalyst, and (3) a stabilizing amount of scavenging silaneof the formula ##STR7## where R¹, R², X and c are as previously defined,f is an integer equal to 1 to 4 inclusive, and the sum of c+f is equalto 1 to 4 inclusive. In addition, an effective amount of a curingaccelerator selected from substituted guanidines, amines and mixturesthereof is used.

In a further aspect of the present invention, there is provided a stableroom temperature vulcanizable polyalkoxy-terminated organopolysiloxanecomposition curable under ambient conditions to a tack-free,substantially acid-free elastomer comprising,

(A) 100 parts of a polyalkoxy-terminated organopolysiloxane of Formula(6);

(B) 0 to 10 parts of a cross-linking silane of Formula (4);

(C) an effective amount of condensation catalyst, and

(D) a stabilizing amount of scavenging silane of Formula (7).

Also included within the scope of the present invention is a method ofmaking a room temperature vulcanizable organopolysiloxane compositionunder substantially anhydrous conditions utilizing an effective amountof a condensation catalyst with a silanol-terminated organopolysiloxaneand a polyalkoxysilane cross-linking agent, the improvement whichcomprises (1) adding to the silanol-terminated organopolysiloxane astabilizing amount of a polyalkoxysilane which is both a scavenger forhydroxy functional groups and a cross-linking agent of the formula##STR8## where R¹, R², X, a and b are as previously defined, andthereafter adding an effective amount of a condensation catalyst,whereby improved stability is achieved in the resulting room temperaturevulcanizable organopolysiloxane composition.

Another method of the present invention is making a room temperaturevulcanizable organopolysiloxane composition under substantiallyanhydrous conditions utilizing an effective amount of a condensationcatalyst with an organopolysiloxane wherein the silicon atom at eachpolymer chain end is terminated with at least two alkoxy radicals, whichinvolves the improvement which comprises adding to saidpolyalkoxy-terminated organopolysiloxane; (1) a stabilizing amount of asilane scavenger for hydroxy functional groups of the formula, ##STR9##where R¹, R², X, c and f are as previously defined, and (2) an effectiveamount of a condensation catalyst, whereby improved stability isachieved in the resulting room temperature vulcanizableorganopolysiloxane composition.

In an additional aspect of the present invention, there is provided amethod of making a stable, one-package room temperature vulcanizablepolyalkoxy-terminated organopolysiloxane composition which comprisesagitating, under substantially anhydrous conditions, a room temperaturevulcanizable material selected from

(i) a mixture comprising on a weight basis

(a) 100 parts of a silanol-terminated polydiorganosiloxane consistingessentially of chemically combined units of Formula (2),

(b) an amount of silane of Formula (3) sufficient to scavenge available--OH in the RTV composition and provide up to 3% by weight excess, basedon the weight of RTV composition,

(c) 0 to 10 parts of the cross-linking silane of Formula (4),

(d) an effective amount of a condensation catalyst, and

(e) 0 to 5 parts of curing accelerator selected from substitutedguanidines, amines, and mixtures thereof wherein, the condensationcatalyst is added after the silanol-terminated polydiorganosiloxane andscavenging silane are mixed; and

(ii) a mixture comprising,

(a) 100 parts of the polyalkoxy-terminated organopolysiloxane of Formula(6),

(b) 0 to 10 parts of the cross-linking silane of Formula (4),

(c) an effective amount of a condensation catalyst,

(d) a stabilizing amount of silane scavenger of Formula (7), and

(e) 0 to 5 parts of curing accelerator selected from substitutedguanidines, amines and mixtures thereof.

Radicals included within R of Formulas (2) and (6) are, for example,aryl radicals and halogenated aryl radicals, such as phenyl, tolyl,chlorophenyl, naphthyl; aliphatic and cycloaliphatic radicals, forexample, cyclohexyl, cyclobutyl; alkyl and alkenyl radicals, such asmethyl, ethyl, propyl, chloropropyl, vinyl, allyl, trifluoropropyl; andcyanoalkyl radicals, for example, cyanoethyl, cyanopropyl, cyanobutyl.Radicals preferably included within R¹ are, for example, C.sub.(1-8)alkyl radicals, for example, methyl, ethyl, propyl, butyl, pentyl;C.sub.(7-13) aralkyl radicals, for example, benzyl; phenethyl;alkylether radicals such as 2-methoxyethyl; alkylester radicals, forexample 2-acetoxyethyl; alkylketone radicals, for example1-butan-3-onyl; alkylcyano radicals, for example 2-cyanoethyl. Radicalsincluded with R² are the same or different radicals included within Rradicals. In Formulas (1-7), where R, R¹, and R², can be more than oneradical, these radicals can be the same or different.

Some of the scavengers for chemically combined hydroxy radicals includedwithin one or more of Formulas (3), (5), and (7), are, for example,

Oximatosilanes such as,

methyldimethoxy(ethylmethylketoximo)silane;

methylmethoxybis-(ethylmethylketoximo)silane;

methyldimethoxy(acetaldoximo)silane.

Carbamatosilanes such as,

methyldimethoxy(N-methylcarbamato)silane;

ethyldimethoxy(N-methylcarbamato)silane.

Enoxysilanes such as,

methyldimethoxyisopropenoxysilane;

trimethoxyisopropenoxysilane;

methyltri-iso-propenoxysilane;

methyldimethoxy(but-2-ene-2-oxy)silane;

methyldimethoxy(1-phenylethenoxy)silane;

methyldimethoxy-2(1-carboethoxy-propenoxy)silane.

Aminosilanes such as,

methylmethoxydi-N-methylaminosilane; vinyldimethoxymethylaminosilane;tetra-N,N-diethylaminosilane methyldimethoxymethylaminosilane;

methyltricyclohexylaminosilane;

methyldimethoxyethylaminosilane;

dimethyldi-N,N-dimethylaminosilane;

methyldimethoxyisopropylaminosilane dimethyldi-N,N-diethylaminosilane.

Amidosilanes such as,

ethyldimethoxy(N-ethylpropionamido)silane;methylmethoxydi(N-methylacetamido)silane;

methyldimethoxy(N-methylacetamido)silane;methyltri(N-methylacetamido)silane;

ethyldimethoxy(N-methylacetamido)silane;methyltri(N-methylbenzamido)silane;

methylmethoxybis(N-methylacetamido)silane;

methyldimethoxy(caprolactamo)silane.

trimethoxy(N-methylacetamido)silane.

Imidatosilanes such as,

methyldimethoxyethylacetimidatosilane;

methyldimethoxypropylacetimidatosilane;

Ureidosilanes such as,

methyldimethoxy(N,N',N'-trimethylureido)silane;

methyldimethoxy(N-allyl-N',N'-dimethylureido)silane;

methyldimethoxy(N-phenyl-N',N'-dimethylureido)silane.

Isocyanatosilanes such as,

methyldimethoxyisocyanatosilane;

dimethoxydiisocyanatosilane;

Thioisocyanatosilanes such as

methyldimethoxythioisocyanatosilane;

methylmethoxydithioisocyanatosilane.

In addition, note the disclosure of patent application Chung, entitledNovel RTV Silicone Compositions and Processes Docket 60Si-569 Ser. No.338,518, Filed Jan. 11, 1982, which discloses the use of certainpyrolidone silanes as scavengers in the composition of the instantcomposition. Such pyrolidonal silanes are amide silanes in the foregoingdefinition of scavengers that was given previously. Such cyclic amidesilanes are more specifically described in the foregoing Chung docketfor reference purposes.

In addition, Formula (5) scavenging silanes include silanes such asmethyltris(N-methylacetamido)silane; tetra(isopropenoxy)silane. Alsoincluded are silanes having different leaving groups such asdiethylamino(N-methylcarbamato)isopropenoxy(N-allylN',N'-dimethylureido)silane.

Some of the cross-linking polyalkoxysilanes included within Formula (4)are, for example, methyltrimethoxysilane; methyltriethoxysilane;ethyltrimethoxysilane; tetraethoxysilane; vinyltrimethoxysilane; etc.

Among the curing accelerators which can be used in the practice of theinvention are silyl substituted guanidines having the formula, ##STR10##where R¹ is as previously defined, Z is a guanidine radical of theformula, ##STR11## R³ is divalent C.sub.(2-8) alkylene radical, R⁴ andR⁵ are selected from hydrogen and C.sub.(1-8) alkyl radicals and g is aninteger equal to 1 to 3 inclusive. In addition, alkyl substitutedguanidines having the formula, ##STR12## where R⁴ and R⁵ are aspreviously defined and R⁶ is a C.sub.(1-8) alkyl radical, also can beemployed. Some of the silyl substituted guanidines included within theabove formula are shown by Takago U.S. Pat. Nos. 4,180,642 and4,248,993.

In addition to the above substituted guanidines, there can be usedvarious amines, for example, di-n-hexylamine, dicyclohexylamine,di-n-octylamine, hexamethoxymethylmelamine, and silylated amines, forexample, γ-aminopropyltrimethoxysilane andmethyldimethoxy-di-n-hexylaminosilane.Methyldimethoxy-di-n-hexylaminosilane acts as both a scavenger andcuring accelerator. The primary amines, secondary amines, silylatedsecondary amines are preferred, and secondary amines, and silylatedsecondary amines are particularly preferred. Silylated secondary aminessuch as alkyldialkoxy-n-dialkylaminosilanes and guanidines such asalkyldialkoxyalkylguanidylsilanes which are useful as cure acceleratorsherein also act as scavengers and, in certain instances, as stabilizersin the compositions of this invention.

It should be noted that in the foregoing compositions, it is disclosedthat the composition may be prepared either in the alternative by firstend-capping the silanol terminated diorganopolysiloxane polymer with analkoxy functional cross-linking agent and then adding a scavenger, oralternatively, it may be produced by mixing the scavenger, thecross-linking agent, and the silanol terminated diorganopolysiloxanepolymer at the same time to produce a desired one-component RTV mixturealong with the other ingredients, or there may be applied mixtures ofeither procedure.

Irrespective of which composition is utilized, the silanol terminateddiorganopolysiloxane polymer preferably has the formula ##STR13## whereR as previously defined is a C.sub.(1-13) monovalent substituted orunsubstituted hydrocarbon radical, preferably methyl or a mixture of amajor amount of methyl and a minor amount of phenyl, cyanoethyl,trifluoropropyl, vinyl, and mixtures thereof and n is an integer havinga value of from about 50 to about 2500, with a cross-linking silanehaving hydrolyzable radicals attached to silicon.

The production of such polymers is well known in the art and it will notbe gone into here. An example of the use as well as explanation as tothe preparation of such polymers is for instance to be found in Lampe etal, U.S. Pat. No. 3,888,815 which is hereby incorporated by reference.Preferably the silanol polymer base viscosity is in the range of 30,000to 500,000 centipoise at 25° C.

The condensation catalyst may either be a metal salt of a carboxylicacid or it can be a titanium salt or a titanium chelate. Preferably, thecheaper tin soaps are utilized. Tin soaps allow the cure of thecomposition to proceed at a sufficiently fast rate as compared totitanium chelate catalysts and they are not as expensive.

Effective amounts of the condensation catalysts which can be used in thepractice of the present invention to facilitate the cure of the RTVcompositions are, for example, 0.001 to 1 part based on the weight of100 parts of the silanol-terminated polydiorganosiloxane of Formula (8).There are included tin compounds, for example, dibutyltindilaurate;dibutyltindiacetate; dibutyltindimethoxide; carbomethoxyphenyl tintri-suberate; tin octoate; isobutyl tin triceroate; dimethyl tindibutyrate; dimethyl tin di-neodeconoate; triethyl tin tartrate; dibutyltin dibenzoate; tin oleate; tin naphthenate; butyltintri-2-ethylhexoate;tinbutyrate. The preferred condensation catalysts are tin compounds suchas dibutyltindiacetate and dibutyltindilaurate is particularlypreferred.

Titanium compounds which can be used are, for example,1,3-propanedioxytitanium bis(ethylacetoacetate);1,3-propanedioxytitanium bis(acetylacetonate); diisopropoxytitaniumbis(acetylacetonate); titanium naphthenate; tetrabutyltitanate;tetra-2-ethylhexyltitanate; tetraphenyltitanate; tetraoctadecyltitanate;ethyltriethanolaminetitanate. In addition beta-dicarbonyltitaniumcompounds as shown by Weyenberg U.S. Pat. No. 3,334,067 can be used ascondensation catalysts in the present invention.

Zirconium compounds, for example, zirconium octoate, also can be used.

Further examples of metal condensation catalysts are, for example, lead2-ethyloctoate; iron 2-ethylhexoate; cobalt 2-ethylhexoate; manganese2-ethylhexoate; zinc 2-ethylhexoate; antimony octoate; bismuthnaphthenate; zinc naphthenate; zinc stearate.

Examples of nonmetal condensation catalysts are hexylammonium acetateand benzyltrimethylammonium acetate.

Various fillers and pigments can be incorporated in the silanol oralkoxy-terminated organopolysiloxane, such as for example, titaniumdioxide, zirconium silicate, silica aerogel, iron oxide, diatomaceousearth, fumed silica, carbon black, precipitated silica, glass fibers,polyvinyl chloride, ground quartz, calcium carbonate, etc. The amountsof filler used can obviously be varied within wide limits in accordancewith the intended use. For example, in some sealant applications, thecurable compositions of the present invention can be used free offiller. In other applications, such as the employment of the curablecompositions for making binding material on a weight basis, as much as700 parts or more of filler, per 100 parts of organopolysiloxane can beemployed. In such applications, the filler can consist of a major amountof extending materials, such as ground quartz, polyvinylchloride, ormixtures thereof, preferably having an average particle size in therange of from about 1 to 10 microns.

The compositions of the present invention also can be employed asconstruction sealants and caulking compounds. The exact amount offiller, therefore, will depend upon such factors as the application forwhich the organopolysiloxane composition is intended, the type of fillerutilized (that is, the density of the filler and its particle size).Preferably, a proportion of from 10 to 300 parts of filler, which caninclude up to about 35 parts of a reinforcing filler, such as fumedsilica filler, per 100 parts of silanol-terminated organopolysiloxane isutilized.

In the practice of the invention, the room temperature vulcanizablecompositions can be made by agitating, for example stirring, a mixtureof materials which can consist of the silanol terminatedpolydiorganosiloxane, which hereinafter will include Formula (8) orpolymer consisting essentially of Formula (2) units along with thescavenging silane of Formula (3), and cross-linking silane of Formula(4), which is preferred where the blending is performed in thesubstantial absence of atmospheric moisture. Thereafter the condensationcatalyst is added also in the substantial absence of atmosphericmoisture.

As used hereinafter, the expressions "moisture-free conditions" and"substantially anhydrous conditions," with reference to making the RTVcompositions of the present invention, mean mixing in a dry box, or in aclosed container which has been subjected to vacuum to remove air, whichthereafter is replaced with a dry inert gas, such as nitrogen.Experience has shown that sufficient scavenging silane of Formula (3)should be utilized as previously defined. Temperatures can vary fromabout 0° C. to about 180° C. depending upon the degree of blending, thetype and amount of filler.

A preferred procedure for making the RTV composition of the presentinvention is to agitate under substantially anhydrous conditions, amixture of the silanol terminated polydiorganosiloxane, filler and aneffective amount of the scavenging silane of Formula (3) sufficient toeffect the substantial elimination of hydroxy functional radicals and toend cap the polymer. This "end capping" and scavenging procedure canrequire several minutes, hours, or even days, depending upon suchfactors as the nature of the X leaving group, the number of --OR¹radicals on the scavenging silane, etc. There then can be added to thesubstantially silanol-free mixture, the condensation catalyst, thecross-linking silane, or mixture thereof, along with other ingredients,for example, the curing accelerator and pigments. A stabilizing excessof the scavenging silane can be used in the initial or final stages ofthe mixing procedure if desired in amounts previously defined.

Irrespective of which mixing procedure is utilized, the preferablyone-component RTV system will be obtained in accordance with the Whiteet al disclosure which is shelf stable and has a sufficiently fast curerate under most conditions. For more details as to the preparation ofsuch compositions, one is referred to White et al, U.S. Pat. No.4,395,526. However, the invention of the instant case does not lie insuch one-component systems by themselves but lies in the particularlydefined adhesion promoters of Formula 1 for such a system. In such aformula, R¹⁰ and R¹¹ are C₁₋₈ monovalent hydrocarbon radicals, and tvaries from 0 to 3 and is preferably 0. The R¹⁰ and R¹¹ radicals areselected from alkyl radicals, methyl, ethyl, propyl, etc., alkenylradicals such as vinyl, allyl, etc., cycloalkyl radicals such ascyclohexyl, cycloheptyl, etc., mononuclear aryl radicals such asmethyl-phenyl, etc., and fluoroalkyl radicals such as3,3,3-trifluoropropyl. Most preferably, R¹⁰ and R¹¹ are selected frommethyl or ethyl and the definition of these symbols is the same in theformulas below.

The Z radical in Formula (1) is generally a saturated, unsaturated oraromatic hydrocarbon residue which may be further functionalized by amember selected from a class consisting of amino, ether, epoxy,isocyanato, cyano, acryloxy, acyloxy and multiples and combinationsthereof. Generally, such adhesion promoters may be utilized anywhere upto an effective amount in the composition which can vary somewhat fromadhesion promoter to adhesion promoter. Too much of the adhesionpromoter will not yield any further desirable results and in someinstances may detract from the physical properties of the cured RTVcomposition. Accordingly, generally the adhesion promoter is utilized ata concentration of anywhere from 0.1 to 10 parts and more preferablyfrom 0.1 to 5 parts by weight per 100 parts by weight of thepolyalkoxyorganopolysiloxane, or per 100 parts of the silanol terminateddiorganopolysiloxane polymer of Formula (8). The concentration will besubstantially the same for both situations since the endcap groups addvery little to the molecular weight of the polymer, whether it issilanol terminated or endcapped.

Preferably, the adhesion promoter in one case has the formula ##STR14##where R¹⁰, R¹¹, t are as previously defined, and R¹² is a C.sub.(2-12)divalent hydrocarbon radical, R¹³, R¹⁴ are selected from the classconsisting of hydrogen, amine radicals, and C.sub.(1-8) hydrocarbonsubstituted amine radicals and C.sub.(1-8) monovalent hydrocarbon groupsand mixtures thereof.

Specifically, R¹² is selected from alkylene and arylene substituted orunsubstituted divalent hydrocarbon radicals of 2-12 carbon atoms andmore preferably from 2-8 carbon atoms. The radicals R¹³ and R¹⁴ can behydrogen or any of the C.sub.(1-8) monovalent hydrocarbon radicalsdisclosed for the R¹⁰ and R¹¹ radicals. However, preferably, they can beselected from amine radicals and substituted amine radicals, such as forinstance, aminoethyl. It is postulated that most of the strictly amineor nitrogen functionalized adhesion promoters of U.S. Pat. No. 3,888,815which are disclosed in that patent can be utilized as adhesion promotersin the instant case. For a fuller description of such compounds, one isreferred to the disclosure of the foregoing Bessemer et al patent, U.S.Pat. No. 3,888,815. Such compounds can be made, for instance, as set forin disclosure U.S. Pat. No. 2,930,809 and U.S. Pat. No. 2,971,864 whichare incorporated by reference. Preferable compounds within the Formula(9) above are for instance, 3-(2-aminoethylamino)-propyltrimethoxysilane. Other compounds are γ -aminopropyltriethoxysilane andγ-aminopropyltrimethoxysilane. Other preferable amine adhesion promotersthat can be utilized in the instant invention come within the scope ofFormula (9) above are as follows:

γ-aminopropylmethyldiethoxysilane

γ-aminopropylmethyldimethoxysilane

Bis[3-(triethoxysilyl)propyl]amine

Bis[3-(triethoxysilyl)propyl]ethylenediamine

3-(2-aminoethylamino)-propyldimethoxy-t-butoxysilane

methacryloxyethylaminoethylaminopropyltrimethoxysilane

methylaminopropyltrimethoxysilane

methylaminopropyltriethoxysilane

(N,N-dimethyl-3-amino)propyltrimethoxysilane

N,N-dimethylaminophenyltriethoxysilane

N,N-dimethylaminoethyldimethoxysilane

Accordingly, although most silanes functionalized by amines were notexperimented with, it is envisioned that most silanes functionalized byamines should operate in the instant invention as adhesion promoters.These compounds are readily available in the silicone industry and fromspecialty chemical houses and can be readily prepared by reacting theappropriate unsaturated amine intermediate with a trimethoxysilane or ahydride silane with the appropriate substituent groups in the presenceof a platinum catalyst to produce the desired compound. Further thereare other processes for producing these compounds. More detail will notbe given as to such preparations since such is well known in the art asis evidenced by the foregoing U.S. Pat. No. 3,888,815.

Another adhesion promoter that can be utilized in the instant inventionis one of the formula ##STR15## where G is selected from R²⁰ or (R²¹O)_(3-b) R_(b) ^(20L) -Si-R²² radical, styryl, vinyl, allyl,chloroallyl, cyclohexenyl, R²² is a C.sub.(2-12) divalent hydrocarbonradical selected from alkylenearylene, alkylene, cycloalkylene andhalosubstituted such divalent hydrocarbon radicals, and R²⁰ and R²¹ areselected from the same radicals as R¹⁰ and R¹¹ and also cyano alkyl, andb varies from 0 to 3.

For more information as to such compounds, one is referred to thedisclosure of Beers, U.S. Pat. No. 4,100,129, and Berger, U.S. Pat. No.3,821,218 which is hereby incorporated by reference.

The most preferred adhesion promoters within Formula (10) are1,3,5-tristrimethoxysilylpropylisocyanate andbis-1,3-trimethoxysilylpropylisocyanurate. Again, much detail will notbe given as to the preparation of such compounds. Such compounds areprepared by taking the corresponding alkoxy hydride silane and reactingit with the unsaturated isocyanurate or cyanurate in the presence of aplatinum catalyst whereupon the hydride adds on to the unsaturated groupsuch as the allyl group of the isocyanurate nucleus. The radical R²² canbe selected from any divalent hydrocarbon radical substituted orunsubstituted so long as it does not interfere with the adhesionpromoter activities of the compound. It should be noted that highlycomplicated compounds are not desired as they are more difficult andthus more expensive to prepare and obtain. Other specific compoundswithin the scope of Formula (10) above are as follows:

1,3,5-tristrimethoxysilylpropylisocyanurate

1,3,5-tristrimethoxysilylethylisocyanurate

1,3,5-trismethyldimethoxysilylpropylisocyanurate

1,3,5-trismethyldiethoxysilylpropylisocyanurate

Another adhesion promoter compound which may be utilized in the instantinvention is, for instance, one having the general formula, ##STR16##wherein the above Formula is within the scope of Formula (1) and whereR¹⁰ and R¹¹, t are as previously defined, R¹² is a C.sub.(2-12) divalenthydrocarbon radical, R¹⁶ is a C.sub.(2-12) divalent hydrocarbon radicaland R¹⁷ is selected from the class consisting of hydrogen and aC.sub.(1-8) monovalent hydrocarbon radical. The radicals R¹² and R¹⁶ canbe any divalent hydrocarbon radicals such as alkylene radicals, aryleneradicals, alkylenearylene radicals, both saturated and unsaturated asdisclosed previously for the other compounds, and can be substituted orunsubstituted with various groups such as halogen groups, ether groups,ester groups and other hydrocarbon groups. The radical R¹⁷ can behydrogen a monovalent hydrocarbon radical the same as previously definedfor R¹⁰ and R¹¹ and is most preferably hydrogen. The most preferredcompound within the scope of Formula (11) above is γ-glycidoxypropyltrimethoxysilane. Other specific compounds within formula (11)above which are preferred as adhesion promoters in the instant inventionare for instance,

γ-glycidoxyproylmethyldimethoxysilane

γ-glycidoxypropyltriethoxysilane

γ-glycidoxypropylmethyldiethoxysilane

γ-glycidoxyethyltrimethoxysilane

These compounds can be made by silicone producers as described in theliterature or obtained from specialty chemical supply houses.

One process for producing such a compound such as that in Formula (11)is for instance taking an allyl glycidyl ether and reacting it withtrimethoxyhydridesilane in the presence of a platinum catalyst. Thisreaction which is well known in the art is to add the trimethoxysilaneonto th allyl group of the glycidyl ether so as to produce the desiredspecific adhesion promoter that was disclosed above. This generalreaction may be followed to produce other compounds coming within thescope of Formula (11) above.

Another group of compounds coming within the scope of Formula (11) aboveis adhesion promoters which have the formula, ##STR17## where R¹⁰ andR¹¹, t are as previously defined, R¹² is a C.sub.(2-12) divalenthydrocarbon radical and Q is an epoxy functional radical having asaturated hydrocarbon ring appended thereto. The radical R¹² can be anydivalent hydrocarbon radical substituted or unsubstituted, saturated orunsaturated, with substituent groups being selected from monovalenthydrocarbon groups, halogen groups, ether groups, ester groups, etc. Itshould be understood that in all foregoing formulas of adhesionpromoters given in this application, the R¹² radical can be any divalentradical or 2 to 12 carbon atoms having monovalent hydrocarbon radicals,halogen radicals, ester radicals, ether radicals, and other radicalssubstituent thereto and R¹² radicals can be saturated or unsaturated andsubstituted or unsubstituted. Specific examples of such radicals arealkylene and arylene radicals and alkylenearylene combination radicals.A specific adhesion promoter coming within the scope of Formula (12)above is β-(3,4-epoxycyclohexyl)ethyltrimethoxy silane. Other compoundscoming with the scope of Formula (12) above are as follows:

β-(3,4 epoxycyclohexyl)propyltrimethoxysilane

β-(3,4 epoxycyclohexyl)ethyltriethoxysilane

β-(3,4 epoxycyclohexyl)ethylmethyldimethoxysilane

β-(3,4 epoxycyclohexyl)ethylmethyldiethoxysilane

β-(3,4 enoxycyclohexyl)propylmethyldimethoxysilane

β-(3,4 epoxycyclohexyl)ethyltris(methoxyethoxysilane)

It should be noted that the Z radical in Formula (1) can also be anunsaturated radical such as vinyl or allyl radical of C.sub.(2-12)carbon atoms and can be substituted, unsubstituted, with groups such asmonovalent hydrocarbon radicals, halogen groups, ester groups, and ethergroups. Preferably, Z is C.sub.(2-12) olefinic hydrocarbon groups suchas vinyl or ally. The preferred compound coming within the scope of thatformula, Formula (1), of the above definition is vinyltrimethoxysilane.Other compounds coming within the scope of Formula (1) above are asfollows:

vinyltriethoxysilane

allyltrimethoxysilane

allyltriethoxysilane

vinylmethyldiethoxysilane

vinyltrimethoxysilane

vinyltris(2-methoxyethoxy)silane

Such compounds where Z is an olefinic radical such as a vinyl compoundcan be produced for instance by reacting silicon metal with vinylchloride or allyl chloride in the presence of a copper catalyst at hightemperatures to produce the foregoing vinylchlorosilane and then takingthis intermediate and alkoxylating it. This is a procedure well known inthe art to silicone producers and such chemicals are readily available.

With respect to the compounds of formula (12) above, such compounds canbe produced by reacting a hydride trimethoxy silane with avinylcyclohexane oxide in the presence of a platinum catalyst at roomtemperatures or temperatures in the range of room temperature to 150° C.and then purifying the resulting product by distillation or other meansthat yield the desired-(3,4-epoxycyclohexyl)ethyltrimethoxy silane.Other compounds within the scope of Formula (12) above, can be producedin the same manner utilizing the same procedure as the above as is wellknown in the art.

Another compound within the scope of the present invention and withinthe scope of compounds of Formula (1) is one of the formula ##STR18##where R¹⁰, R¹¹, t are as previously defined, R¹² is a C.sub.(2-12)divalent hydrocarbon radical in accordance with the previous definitiongiven before for such radicals in the other formulas, and R²⁵ and R²⁶are selected from a class consisting of hydrogen and C.sub.(1-8)monovalent hydrocarbon radicals.

The R²⁵ and R²⁶ radicals can be any of the radicals previously given forR¹⁰ and R¹¹. More detail will not be given since such substituent groupshave been sufficiently defined with respect to R¹⁰ and R¹¹. Further,such compounds of Formula (13) can be produced by reacting an olefinicisocyanate such as allyl isocyanate with hydrotrimethoxysilane in thepresence of a platinum catalyst. In all of the cases it has beendisclosed that an alkoxylated product is being used such astrialkoxyhydride silane. This is for the case where t is equal to 0. Inthe case where t has a value of 1, 2, or 3 instead of the alkoxylatedproduct, there can be utilized the corresponding R¹¹ intermediate toobtain a desired product. Accordingly, in the present case, if analkoxylated product is not desired or a semialkoxylated product isdesired, then of course instead of the hydride trialkoxysilane therewill be used a hydride monoalkyl, dialkyl, silane. Such intermediatesare well known in the art. At any rate, the compound of Formula ( 13)can be produced by adding on the desired hydride intermediate to theolefinic isocyanate compound to produce the desired reaction product.

Accordingly, specifically for the compounds of the instant case, allylisocyanate may be reacted with trimethoxy hydride silane to produce thedesired γ-isocyanatopropyltrimethoxysilane as the desired end product inthe presence of the platinum catalyst under much the same conditions aswas used to produce the other products. The compound does not need tohave three methoxy groups. The appropriate intermediate can be utilizedso that there can be 0, 1, 2, or 3 methoxy groups as is desired. Suchintermediates are well known in the art. Along with theγ-isocyanatopropyltrimethoxysilane other compounds coming within thescope of Formula (13) are as follows:

isocyanatopropyltriethoxysilane

isocyanatopropylmethyldimethoxysilane

isocyanatopropylmethyldiethoxysilane

isocyanatoethyltrimethoxysilane

Another group of adhesion promoters coming within the scope of Formula(1) above are compounds of the formula ##STR19## where R¹⁰, R¹¹, t areare previously defined and R¹² is a C.sub.(2-12) divalent hydrocarbonradical and may be any of the R¹² radicals previously defined in thisapplication; that is saturated or unsaturated, substituted orunsubstituted. A preferred specific compound within the scope of Formula(14) above is γ-cyanopropyltrimethoxysilane. Other specific compoundsare as follows:

3-(cyanoethoxy)-3-methylbutenyltrimethoxysilane

β-cyanoethylmethyldimethoxysilane

β-cyanoethyltriethoxysilane

β-cyanoethyltrimethoxysilane

2-cyanoethylmethyldiethoxysilane

3-cyanopropyltriethoxysilane

cyanopropylmethyldimethoxysilane

1-cyanoethyltris(methoxyethoxy)silane

Such compounds are produced by reacting an olefinic cyanide with atrichlorohydride silane in the presence of a platinum catalyst undermuch the same conditions that the other compounds were reacted toproduce the desired intermediate and then alkoxylating this intermediateso as to produce the preferable γ-cyanopropyltrimethoxysilane.Accordingly, one specific type of reaction could be, for instance, allylcyanide reacted with trichlorosilane. In this reaction the chlorosilaneis reacted wth the cyanide, otherwise, since the methoxy group willreact with the cyanide group to lower the yield of the desired productif the methoxylated intermediate is used in the addition reaction withthe platinum catalyst. Such reactions as was stated previously, are wellknown in the art for the production of such compounds, and suchcompounds may be produced and are well known to silicone manufacturers.

Another group of compounds coming with the scope of Formula (1) aboveand which may be utilized as adhesion promoters are compounds of theformula ##STR20## where R¹⁰, R¹¹ and t are as previously defined. InFormulas (9-15), t can vary from 0 to 3 and R¹² is a C.sub.(2-12)divalent hydrocarbon radical as previously defined, Further R³⁰ and R³¹are selected from class consisting of hydrogen, C.sub.(1-8) monovalenthydrocarbon radicals, and mixtures thereof. It should be noted that R³⁰and R³¹ can be substituted or unsubstituted. A preferred compound comingwithin the scope of Formula (15) above isγmethacryloxypropyltrimethoxysilane. Other specific compounds comingwith the Formula (15) which can be utilized in the instant invention

γ-acryloxypropyltrimethoxysilane

γ-acryloxypropyltriethoxysilane

γ-methacrylpropyltriethoxysilane

γ-methacryloxypropyltris(methoxyethoxy)silane

γ-methacryloxypropylmethyldimethoxysilane

γ-methacryloxyethyltrimethoxysilane

Such compounds can be produced by taking the corresponding olefinicacrylate and reacting it with a hydride alkoxy silane in the presence ofa platinum catalyst under much the same conditions as in the productionof the other adhesion promoters. Such compounds are as set forth in thepatent application of Keating, Ser. No. 109,727, filed Jan. 4, 1980, andthe preparation and production of such compounds are more fullydisclosed in the foregoing patent application. In accordance with theforegoing disclosure of Keating, such compounds can be prepared by aworker skilled in the art with facility either utilizing the methoddisclosed above or utilizing other methods.

The method disclosed above is the simplest method for the preparation ofsuch compounds.

Finally, another class of compounds coming within the scope of Formula(1) which can be utilized as adhesion promoters in the invention of theinstant case is compounds of the Formula ##STR21## where R¹⁰, R¹¹, t areas previously defined, R¹² is a C.sub.(2-12) divalent hydrocarbonradical, as previously defined, and R³³ is a C.sub.(1-8) monovalenthydrocarbon radical. The R¹² radical can be any of the R¹² radicals thathave been given previously in the preparation of the other class ofcompounds and may be substituted or unsubstituted and saturated orunsaturated. Preferably, R³³ is methyl and the compound isacetoxypropyltrimethoxysilane. Other compounds coming within the scopeof Formula (16) above are as follows:

2-acetoxyethyltrimethoxysilane

2-acetoxyethyltriethoxysilane

3-benzoxypropylmethyldimethoxysilane

3-benzoxypropyltrimethoxysilane

3-benzoxypropyltriethoxysilane

3-benzoxypropylmethyldiethoxysilane

2-acetoxypropylmethyldimethoxysilane

2-acetoxypropylmethyldiethoxysilane

2-acetoxypropyltriethoxysilane

Again, the above class of compounds of Formula (16) above may beproduced by any method but it is more preferred to be produced byreacting the appropriate hydride silane with an olefinic carboxylate oracyloxy functional compound in the presence of a platinum catalyst undermuch the same conditions as was utilized to produce the other compounds.The conditions for such reactions can take place from room temperatureto 120° to 150° C. and the reaction is an addition reaction which takesplace readily in a period of time varying from 30 minutes to 24 hours.The reaction can take place either under atmospheric pressure or vacuum.Utilizing such a procedure, and the above disclosures, a worker skilledin the art can produce the above compounds.

Furthermore, most of the above chemicals can be obtained from specialtychemical houses such as: Petrarch Systems, Inc., P.O. Box 141,Levittown, Pa., 19059; Union Carbide, Connecticut; Dow-Corning,Michigan; and Silar Laboratories, 10 Alplaus Road, Scotia, N.Y., 12302.

The foregoing adhesion promoters may be incorporated into theone-component RTV compositions in any fashion. Thus they may beincorporated into the system by first producing the endcap polymer, andthen adding the scavenger, and then the adhesion promoter, filler, andother ingredients. Alternatively, all the ingredients may be mixedtogether at the same time, or there may be many variations of thesemixing procedures. The most preferred mixing procedure is to end-cap thesilanol polymer with a cross-linking agent first, and then add theadhesion promoter along with the filler condensation catalyst and otheringredients. This produces a more preferable RTV composition with themost desirable properties as well as being the easiest to manufacture.

The Examples given below are given for the purpose of illustrating thepresent invention. They are not given for any purpose of setting limitsor boundaries to the instant invention. All parts in the examples are byweight.

EXAMPLE 1

A suitable mixture equipped with a vacuum line and nitrogen purge wascharged with 100 parts by weight of methyldimethoxy cappedpolydimethylsiloxane polymer of 120,000 centipoise viscosity at 25° C.with 0.6% by weight of di-n-hexylamine, 17 parts ofcyclooctamethyltetrasiloxane treated fumed silica filler, 20 parts of asilanol containing trimethylsiloxy end stopped dimethylpolysiloxanefluid of 100 centipoise viscosity of 25° C., 10 parts by weight of asilanol containing fluid having 20 mole percent of monomethylsiloxyunits, 76 mole percent of dimethylsiloxy units, and 4 mole percent oftrimethylsiloxy units with 0.5 mole percent silanol groups, and 0.2parts of polyether as a thixotrope which is sold under the trade name ofUCON LB-1145 which is a tradename of a polyether sold by the UnionCarbide Corporation, Connecticut. This mixture was agitated under fullvacuum (22 mm Hg) at room temperature for two hours to give an RTV base.To this base was added 2 parts of hexamethyldisilazane and 1 partmethyltrimethoxy silane. Following a 15-minute mix at room temperatureusing a SemKit® mixer, a solution comprised of 1 part3(-2-aminoethylamino) propyltrimethoxysilane and 0.2 parts ofdibutyltindiacetate was added to the RTV composition followed by asecond 15-minute mix at room temperature using a SemKit® mixer.

Following mixing, the material was placed in sealed aluminum tubes andstored for 24 hours at room temperature, 24 hours at 100° C. and 48hours at 100° C. After aging, the material was made into ASTM sheets andallowed to cure three days at room temperature and 50% relativehumidity. After curing, a physical property profile to illustrate theproperties of the composition. The flow rate of the uncured mixture wastested with a flow test jig as described in military specificationMIL-A-46106A. Flow measurement was taken after 3 minutes.

Application Rate

The equipment necessary for the application rate test is as follows:

Equipment

Semco #250 Sealant Gun

Semco #250-C6 6 oz. polyethylene cartridges and #250 polyethyleneplungers.

Compressed Air Source with Regulator, 90±0.5 psig.

Stainless Steel Nozzle--2.000±0.005" length×0.54±0.005" diameter. Centerbored 0.1990"±0.0005" hole. Threaded with 1/2" pipe thread at one end,1/2" length.

Centigrade Thermometer.

Stopwatch.

Aluminum Dishes--23/8" dia.×5/8" deep.

Balance--capable of weighing to 0.1 gm. accuracy.

Standard Conditions: 73±3° F., 50-10% R.H.

Constant Temperature Bath at 23±1° C.

SemKit® Mixer.

Procedure P Sample is checked for temperature; if above 23±1° C.condition the sample until the proper temperature is obtained.

Install the stainless steel nozzle into the cartridge. Insert thecartridge into the Semco gun and connect it to 90±0.5 psi air source.

Extrude a few grams of sealant to clean any entrapped air and to fillthe nozzle.

Extrude the sealant into a tared container for exactly 15 seconds. Caremust be taken to start and stop the air pressure precisely on time toensure a 15 second spacer.

Weigh the tared cup with extruded sealant to determine weight of 15second extruded sealant. Multiply 15 sec. weight by (4) to obtain 60sec. extruded weight. Application rate is reported in gm/min.

Tack-Free Time

Determined by simple finger touch test.

Utilizing these tests, the following data was obtained.

                  TABLE I                                                         ______________________________________                                        Property    24 hr/RT  24 hr/100° C.                                                                     48 hr/100° C.                         ______________________________________                                        Flow, inch  0.8"      --         --                                           Application Rate                                                                          123       --         --                                           g/min.                                                                        Specific Gravity                                                                          1.05      --         --                                           Tack free Time,                                                                           10                                                                (min.)                                                                        ______________________________________                                    

The physical property profile of the composition was also obtained forthe various accelerated and unaccelerated shelf aged samples. Theresults are set forth in Table II below.

                  TABLE II                                                        ______________________________________                                        Property     24 hr/RT 24 hr/100° C.                                                                      48 hr/100° C.                        ______________________________________                                        Hardness, Shore A                                                                           15       16          15                                         Tensile Strength                                                                           254      213         210                                         (psi)                                                                         Elongation (%)                                                                             676      715         653                                         Modulus (75%)                                                                               42       42          44                                         ______________________________________                                    

The composition of this example was also tested for primerless adhesionto aluminum, glass, polyacrylate, polycarbonate, polyvinylchloride andconcrete after the RTV material was aged for 24 hours at roomtemperature. Peel specimens were prepared and allowed to cure for fivedays at room tempera- at 50% relative humidity before pulling. Theresults are given in Table III below.

                  TABLE III                                                       ______________________________________                                                        Peel Adhesion                                                 Substrate       ppi/% Cohesive Failure                                        ______________________________________                                        Glass           56/60                                                         Aluminum (anodized)                                                                           37/80                                                         Aluminum (alclad)                                                                             42/60                                                         Polyacrylate    10/0                                                          Concrete        12/5                                                          Polycarbonate    43/100                                                       PVC             25/10                                                         ______________________________________                                    

As the data in Table III above indicates, the foregoing self-bondingadhesion promoter gave good self-bonding additive properties to thecomposition in the absence of a primer to many substrates. In the caseof some substrates, such as polycarbonates, adhesion was excellent.

EXAMPLE 2

The same composition as in Example 1 was prepared except there waspresent, instead of 3-(2-aminoethylamino)-propyltrimethoxysilane,tri(trimethoxysilylpropyl)isocyanurate at the concentration of 1.50parts. Using the same preparation technique and peel adhesion procedureas outlined in Example 1, the following peel adhesion results wereobtained.

    ______________________________________                                                        Peel Adhesion                                                 Substrate       ppi/% Cohesive Failure                                        ______________________________________                                        Glass            22/100                                                       Aluminum (anodized)                                                                           25/90                                                         Aluminum (alclad)                                                                             28/95                                                         Concrete        33/10                                                         Polyacrylate    0/0                                                           ______________________________________                                    

EXAMPLE 3

The same composition as in Example 1 was prepared except there waspresent, instead of 3-(2-amino-ethylamino)-propyltrimethoxysilane,glycidoxypropyltrimethoxysilane at the concentration of 1.50 parts.Using the same preparation technique and peel adhesion procedure asoutlined in Example 1, the following peel adhesion results wereobtained.

    ______________________________________                                                        Peel Adhesion                                                 Substrate       ppi/% Cohesive Failure                                        ______________________________________                                        Glass            44/100                                                       Aluminum (anodized)                                                                           46/60                                                         Aluminum (alclad)                                                                              55/100                                                       Concrete        32/60                                                         Polyacrylate    0/0                                                           ______________________________________                                    

EXAMPLE 4

The same composition as in Example 1 was prepared except there waspresent, instead of 3-(2-aminoethylamino)-propyltrimethoxysilane,β-(3,4,epoxycyclohexyl)-ethyltrimethoxysilane at the concentration of1.50 parts. Using the same preparation technique and peel adhesionprocedure as outlined in Example 1, the following peel adhesion resultswere obtained.

    ______________________________________                                                        Peel Adhesion                                                 Substrate       ppi/% Cohesive Failure                                        ______________________________________                                        Glass            35/100                                                       Aluminum (anodized)                                                                           35/50                                                         Aluminum (alclad)                                                                              28/100                                                       Concrete        13/0                                                          Polyacrylate    0/0                                                           ______________________________________                                    

EXAMPLE 5

The same composition as in Example 1 was prepared except there waspresent, instead of 3-(2-aminoethylamino)-propyltrimethoxysilane,vinyltrimethoxysilane at the concentration of 1.50 parts. Using the samepreparation technique and peel adhesion procedure as outlined in Example1, the following peel adhesion results were obtained.

    ______________________________________                                                        Peel Adhesion                                                 Substrate       ppi/% Cohesive Failure                                        ______________________________________                                        Glass            35/100                                                       Aluminum (anodized)                                                                           35/95                                                         Aluminum (alclad)                                                                              35/100                                                       Concrete        18/0                                                          Polyacrylate    0/0                                                           ______________________________________                                    

EXAMPLE 6

The same composition as in Example 1 was prepared except there waspresent, instead of 3-(2-aminoethylamino)-propyltrimethoxysilane,γ-isocyanatopropyltrimethoxysilane at the concentration of 1.50 parts.Using the same preparation technique and peel adhesion procedure asoutlined in Example 1, the following peel adhesion results wereobtained:

    ______________________________________                                                        Peel Adhesion                                                 Substrate       ppi/% Cohesive Failure                                        ______________________________________                                        Glass            29/100                                                       Aluminum (anodized)                                                                           9/0                                                           Aluminum (alclad)                                                                              31/100                                                       Concrete        10/0                                                          Polyacrylate    0/0                                                           ______________________________________                                    

EXAMPLE 7

The same composition as in Example 1 was prepared except there waspresent, instead of 3-(2-aminoethylamino)-propyltrimethoxysilane,cyanopropyltrimethoxysilane at the concentration of 1.50 parts. Usingthe same preparation technique and peel adhesion procedure as outlinedin Example 1, the following peel adhesion results were obtained:

    ______________________________________                                                        Peel Adhesion                                                 Substrate       ppi/% Cohesive Failure                                        ______________________________________                                        Glass           29/95                                                         Aluminum (anodized)                                                                           7/0                                                           Aluminum (alclad)                                                                              31/100                                                       Concrete        17/50                                                         Polyacrylate    0/0                                                           ______________________________________                                    

EXAMPLE 8

The same composition as in Example 1 was prepared except there waspresent, instead of 3-(2-aminoethylamino)-propyltrimethoxysilane,methacryloxypropyltrimethoxysilane at the concentration of 1.50 parts.Using the same preparation technique and peel adhesion procedure asoutlined in Example 1, the following peel adhesion results wereobtained:

    ______________________________________                                                        Peel Adhesion                                                 Substrate       ppi/% Cohesive Failure                                        ______________________________________                                        Glass           35/95                                                         Aluminum (anodized)                                                                           8/0                                                           Aluminum (alclad)                                                                             12/5                                                          Concrete        11/0                                                          Polyacrylate    0/0                                                           ______________________________________                                    

EXAMPLE 9

The same composition as in Example 1 was prepared except there waspresent, instead of 3-(2-aminoethylamino)-propyltrimethoxysilane,cyanoethyltrimethoxysilane at the concentration of 1.50 parts. Using thesame preparation technique and peel adhesion procedure as outlined inExample 1, the following peel adhesion results were obtained.

    ______________________________________                                                        Peel Adhesion                                                 Substrate       ppi/% Cohesive Failure                                        ______________________________________                                        Glass            24/100                                                       Aluminum (anodized)                                                                           23/90                                                         Aluminum (alclad)                                                                             27/95                                                         Concrete        14/10                                                         Polyacrylate    0/0                                                           ______________________________________                                    

EXAMPLE 10

The same composition as in Example 1 was prepared except there waspresent, instead of 3-(2-aminoethylamino)-propyltrimethoxysilane,aminopropylmethyldimethoxysilane at the concentration of 1.50 parts.Using the same preparation technique and peel adhesion procedure asoutlined in Example 1, the following peel adhesion results wereobtained:

    ______________________________________                                                        Peel Adhesion                                                 Substrate       ppi/% Cohesive Failure                                        ______________________________________                                        Glass           8/0                                                           Aluminum (anodized)                                                                           15/10                                                         Aluminum (alclad)                                                                             31/50                                                         Concrete        17/10                                                         Polyacrylate    0/0                                                           ______________________________________                                    

EXAMPLE 11

The same composition as in Example 1 was prepared except there waspresent, instead of 3-(2-aminoethylamino)-propyltrimethoxysilane,3-Acetoxypropyltrimethoxysilane at the concentration of 1.50 parts.Using the same preparation technique and peel adhesion procedure asoutlined in Example 1, the following peel adhesion results wereobtained:

    ______________________________________                                                        Peel Adhesion                                                 Substrate       ppi/% Cohesive Failure                                        ______________________________________                                        Glass           27/50                                                         Aluminum (anodized)                                                                           0/0                                                           Aluminum (alclad)                                                                              23/100                                                       Concrete        10/0                                                          Polyacrylate    0/0                                                           ______________________________________                                    

The adhesion promoters of the present case are preferably used with theRTV compositions of Dziark, U.S. Pat. No. 4,417,042. In one instance,Dziark discloses certain preferred silazane, compounds as scavengers forthe RTV systems of White et al., U.S. Pat. No. 4,395,526. The preferredsystems of Dziark, U.S. Pat. No. 4,417,042, comprise first forming apolyalkoxy diorganopolysiloxane polymer and then having a scavengingcompound separate from the cross-linking agent which compound is asilazane monomer or polymer, or certain amine polymeric compounds. Theadhesion promoters of the present case can also be utilized either withthe compositions of White et al., U.S. Pat. No. 4,395,526, or with thecompositions of Dziark, U.S. Pat. No. 4,417,042, along with theadditives disclosed in Beers, Ser. No. 349,537, filed Feb. 17, 1982, toproduce an advantageous one-component, low modulus, fast-curing shelfstable, self-bonding, RTV system. It should be noted that the scavengersof Dziark, U.S. Pat. No. 4,417,042, are separate compounds and inaddition to the cross-linking agent. Such compositions are disclosed inthe White et al., U.S. Pat. No. 4,395,526, in addition to otheralkoxy-functional RTV systems. A short synopsis of the Dziark, U.S. Pat.No. 4,417,042, system is disclosed below. For more information as tosuch scavengers and RTV systems, one is referred to the disclosure ofDziark, U.S. Pat. No. 4,417,042. In accordance with Dziark, U.S. Pat.No. 4,417,042, the present adhesion promoters can be utilized with astable, one-package, substantially anhydrous and substantiallyacid-free, room temperature vulcanizable organopolysiloxane compositionstable under ambient conditions in the substantial absence of moistureover an extended period of time and convertible to a tack-free elastomerhaving (1) an organopolysiloxane wherein the silicon atom at eachpolymer chain end is terminated with at least 2 alkoxy radicals; (2) aneffective amount of a condensation catalys; (3) a stabilizing amount ofscavenger for hydroxy functional groups which is a silicon-nitrogencompound selected from the class consisting of

(A) a silicon-nitrogen compound having the formula ##STR22## where Y isselected from R'" and R₂ "N-- and

(B) a silicon-nitrogen polymer comprising (i) from 3 to 100 mole percentchemically combined structural units selected from the class consistingof units having the formula ##STR23## and (ii) from 0 to 97 mole percentchemically combined structural units represented by the formula ##EQU1##and mixtures thereof where the silicon atoms of said silicon-nitrogenpolymer are joined to each other by a member selected from an SiOSilinkage and a SiNR"Si linkage, the free valences of said silicon atomsother than those joined to oxygen to form a siloxy unit and nitrogen toform a silazy unit are joined to a member selected from and R'" radicaland (R")₂ N radical, and where the ratio of the sum of said R'" radicalsand said (R")₂ N radicals to the silicon atoms of said silicon-nitrogenpolymer has a value of 1.5 to 3, inclusive, and R" is a member selectedfrom the class consisting of hydrogen and monovalent hydrocarbonradicals, and fluoroalkyl radicals, R'" is a member selected fromhydrogen, monovalent hydrocarbon radicals and fluoroalkyl radicals, andc is a whole number equal to 0 to 3, inclusive, and (4) one of theadhesion promoters of the present case.

There is present from 0.5 to 10 parts by weight of the siliconescavenger per 100 parts by weight of the organopolysiloxane. Thesilazane polymers can include cyclic silazanes of chemically combined##STR24## units where R", R'" are as previously defined to provide for aratio of 1.5 to 3.0 of the sum of the R'" and (R")₂ N radicals persilicon atom in said silazane polymer.

The silazane polymer can comprise linear polymers having at least oneunit selected from the class consisting of ##STR25## units, and##STR26## units where R", R'" are as previously defined to provide for aratio of 1.5 to 3 of the sum of the R'" and (R")₂ N radicals per siliconatom in said silazane polymer.

The silazane polymers comprise linear polymers consisting essentially of##STR27## units where R" and R'" are as defined to provide for a ratioof 1.5 to 3.0 of the sum of the R'" and (R")₂ N radicals per siliconatom in said silazane polymer.

The silazane polymers can have at least one unit selected from the classconsisting of ##STR28## units and ##STR29## units where R" and R'" areas previously defined to provide for a ratio of 1.5 to 3 of the sum ofthe R'" and (R")₂ N radicals per silicon atom in said silazane polymer.

The silazane polymer can comprise polymers having a sufficient amount ofunits selected from ##STR30## where R" and R'" are as previously definedto provide for a ratio of 1.5 to 3 of the sum of the R'" and (R")₂ Nradicals per silicon atom in said silazane polymer.

Further, the silazane-siloxane compounds can be copolymers with up to 97mole percent of ##STR31## units with most of the units being selectedfrom ##STR32## where R" and R'", and c are as previously defined toprovide for a ratio of the sum of R'"+(R")₂ N radicals per silicon atomof said silazane-siloxane copolymer of from 1.5 to 3.

The cyclic silazane-siloxane compounds are cyclics consisting ofchemically combined (R'")₂ SiO units and ##STR33## units where R" andR'" are as previously defined.

Further, the silazane nitrogen compounds can be linear and cyclicsilazane having the formula ##STR34## where R" and R'" are as previouslydefined where n is a positive whole number and is preferably 0 to 20,inclusive, and d is a whole number equal to 0 to 1, inclusive, and whered is equal to 0, n is preferably equal to 3 to 7, inclusive.

Further, the silazane nitrogen compound is a polysiloxane having theformula ##STR35## where R", R'" and n are as defined previously and Z isa number selected from R" and --Si(R'")₃.

The silicon nitrogen compound is preferably selected fromhexamethyldisilazane, hexamethylcyclotrisilazane,octamethylcyclotetrasilazane, a silicon nitrogen compound that has theformula ##STR36## and a silicon nitrogen compound that has the formula##STR37## and a silicon nitrogen compound which has the formula,##STR38##

What is claimed is:
 1. A stable, one-package, substantially anhydrousand substantially acid-free, room temperature vulcanizableorganopolysiloxane composition stable under ambient conditions in thesubstantial absence of moisture over an extended period of time andconvertible to a tack-free elastomer comprising: (1) anorganopolysiloxane wherein the silicon atom at each polymer chain end isterminated with at least two alkoxy radicals;(2) an effective amount ofa condensation catalyst; (3) a stabilizing amount of scavenger forhydroxy functional groups; (4) an effective amount of a curingaccelerator selected from the group consisting of substitutedguanidines, amines and mixtures thereof; and (5) an effective amount ofan adhesion promoter having the formula ##STR39## where R¹⁰ and R¹¹ areC₁₋₈ monovalent hydrocarbon radicals, t varies from 0 to 3, and Z is asaturated, unsaturated or aromatic hydrocarbon radical, said radicalbeing further functionalized by a member selected from the groupconsisting of amino, ether, epoxy, isocyanato, cyano, isocyanurate,acryloxy and acyloxy and mixtures thereof.
 2. The composition of claim 1wherein Z is a saturated, unsaturated or aromatic hydrocarbon radicalfurther functionalized by an amine group to provide an adhesion promoterof the formula ##STR40## where R¹⁰ and R¹¹ are C₁₋₈ monovalenthydrocarbon radicals, R¹² is a C₂₋₁₂ divalent hydrocarbon radical, R¹³and R¹⁴ are selected from the group consisting of hydrogen, amineradicals and C₁₋₈ monovalent hydrocarbon radicals and mixtures thereof,and t varies from 0 to
 3. 3. The composition of claim 1 wherein Z is asaturated, unsaturated or aromatic hydrocarbon radical furtherfunctionalized by an isocyanurate group to provide an adhesion promoterof the formula ##STR41## where G is selected from R²⁰ radicals, radicalsof the formula ##STR42## styryl, vinyl, allyl, chloroallyl andcyclohexenyl radicals, where R²⁰ is a C₁₋₈ monovalent hydrocarbonradical or cyanoalkyl radical, R²¹ is a C₁₋₈ monovalent hydrocarbonradical or cyanoalkyl radical, R²² is a C₂₋₁₂ divalent hydrocarbonradical selected from alkylenearylene, alkylene, and cycloalkylene andhalogenated alkylenearylene, alkylene and cycloalkylene and where bvaries from 0 to
 3. 4. The composition of claim 1 wherein Z is asaturated, unsaturated or aromatic hydrocarbon radical furtherfunctionalized by a radical of the formula ##STR43## to provide anadhesion promoter of the formula ##STR44## where R¹⁰ and R¹¹ are C₁₋₈monovalent hydrocarbon radicals, R¹² and R¹⁶ are C₂₋₁₂ divalenthydrocarbon radicals, R¹⁷ is selected from the group consisting ofhydrogen and C₁₋₈ monovalent hydrocarbon radicals, and t varies from 0to
 3. 5. The composition of claim 1 wherein Z is a saturated,unsaturated or aromatic hydrocarbon radical further functionalized by anepoxy group to provide an adhesion promoter of the formula ##STR45##where R¹⁰ and R¹¹ are C₁₋₈ monovalent hydrocarbon radicals, R¹² is aC₂₋₁₂ divalent hydrocarbon radical, Q is an epoxy functional radicalhaving a saturated hydrocarbon ring attached thereto, and t varies from0 to
 3. 6. The composition of claim 1 wherein Z is a saturated,unsaturated or aromatic hydrocarbon radical further functionalized by anisocyanato group to provide an adhesion promoter of the formula##STR46## where R¹⁰ and R¹¹ are C₁₋₈ monovalent hydrocarbon radicals,R¹² is a C₂₋₁₂ divalent hydrocarbon radical, R²⁵ and R²⁶ are selectedfrom the group consisting of hydrogen and C₁₋₈ monovalent hydrocarbonradicals, and t varies from 0 to
 3. 7. The composition of claim 1wherein Z is a saturated, unsaturated or aromatic hydrocarbon radicalfurther functionalized by a cyano group to provide an adhesion promoterof the formula ##STR47## where R¹⁰ and R¹¹ are C₁₋₈ monovalenthydrocarbon radicals, R¹² is a C₂₋₁₂ divalent hydrocarbon radical, and tvaries from 0 to
 3. 8. The composition of claim 1 wherein Z is asaturated, unsaturated or aromatic hydrocarbon radical furtherfunctionalized by an acryloxy radical to provide an adhesion promoter ofthe formula ##STR48## where R¹⁰ and R¹¹ are C₁₋₈ monovalent hydrocarbonradicals, R¹² is a C₂₋₁₂ divalent hydrocarbon radical, R³⁰ and R³¹ areselected from the group consisting of hydrogen and C₁₋₈ monovalenthydrocarbon radicals, and t varies from 0 to
 3. 9. The composition ofclaim 1 wherein Z is a saturated, unsaturated or aromatic hydrocarbonradical further functionalized by an acyloxy radical to provide anadhesion promoter of the formula ##STR49## where R¹⁰ and R¹¹ are C₁₋₈monovalent hydrocarbon radicals, R¹² is a C₂₋₁₂ divalent hydrocarbonradical, R³³ is a C₁₋₈ monovalent hydrocarbon radical and t varies from0 to
 3. 10. The composition of claim 1 wherein the adhesion promoter iscyanoethyltrimethoxysilane.
 11. The composition of claim 1 wherein theadhesion promoter is aminoethylaminopropyltrimethoxysilane.
 12. Thecomposition of claim 1 wherein the adhesion promoter is a mixture ofcyanoethyltrimethoxysilane and aminoethylaminopropyltrimethoxysilane.